The present invention relates to collapsible structures and more particularly to a portable and foldable frame structure for tents, shelters, temporary buildings and the like.
A search of the prior art failed to uncover any prior art references which disclose the foldable frame structure of the present invention. A number of prior art patents were uncovered which disclose a variety of foldable frames for tent-like structures, knock-down buildings and other collapsible enclosures. The following is a listing of the prior art patents uncovered during the aforementioned search:
U.s. pat. No. 1,488,772 PA1 U.s. pat. No. 1,504,889 PA1 U.s. pat. No. 1,772,646 PA1 U.s. pat. No. 1,969,260 PA1 U.s. pat. No. 2,185,588 PA1 U.s. pat. No. 2,311,515 PA1 U.s. pat. No. 2,548,758 PA1 U.s. pat. No. 2,642,162 PA1 U.s. pat. No. 2,733,482 PA1 U.s. pat. No. 3,133,549 PA1 U.s. pat. No. 3,206,897 PA1 U.s. pat. No. 3,826,270 PA1 U.s. pat. No. 3,838,703
Typical of the prior art collapsible frames for tentlike or canopy structures, are the foldable frames disclosed, for example, in the above-listed U.S. Pat. Nos. 1,504,889; 1,772,646; 2,185,588; and 3,826,270. These foldable frames comprise a plurality of rigid, elongate members connected together by means of pivot or hinge joints for limited angular articulation. When erected, the joints connecting adjacent members are rigidly locked against pivotable movement to form a substantially rigid, tent-supporting frame. To collapse the frame, the joint locking devices are released and the members are pivoted about the joints to a folded condition for transportation and/or storage.
A number of these known foldable frames, including, for example, those of the aforementioned U.S. Pat. Nos. 2,185,588; 3,133,549; and 3,826,270 are provided with rigid elongate members connected by hinge joints, successive of ones which are articulatable or foldable in opposite directions so that the elongate members will lie against one another in substantially parallel, side-by-side relation when the frame is in its collapsed condition.
Other examples of prior art foldable structures are typified by the collapsible shelters or buildings disclosed in U.S. Pat. Nos. 2,642,162 and 2,733,482. These arch-like structures are constructed of elongate slats or planks arranged in side-by-side relation and which are pivotally connected together along their adjacent lengthwise edges. The pivotable connecting joints between the slats are arranged so that, during erection of the structure, all joints are essentially articulated in the same direction. These structures are maintained erect by means of a tension element connected between the outermost or lowermost slats.
One of the primary drawbacks of the aforementioned prior art foldable frame devices is their relative design complexity, unreliability and expense, associated particularly with the joint structure, joint locking devices, braces and other components necessary to maintain the frame in a rigid, erected condition. Such complex joint components are often subject to breakage or other operational malfunction which renders the entire frame either wholly inoperative or only marginally operative for its intended purpose. Another disadvantage of many of the prior art foldable frames is that, even when folded, such frames occupy a substantial storage volume and are often cumbersome and difficult to handle and erect.